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Unit 3 Lesson 4 The Terrestrial Planets
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Unit 3 Lesson 4 The Terrestrial Planets
Florida Benchmarks
• SC.8.N.1.5 Analyze the methods used to develop
a scientific explanation as seen in different fields
of science.
• SC.8.E.5.3 Distinguish the hierarchical
relationships between planets and other
astronomical bodies relative to solar system,
galaxy, and universe, including distance, size, and
composition.
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Unit 3 Lesson 4 The Terrestrial Planets
Florida Benchmarks
• SC.8.E.5.7 Compare and contrast the properties
of objects in the Solar System including the Sun,
planets, and moons to those of Earth, such as
gravitational force, distance from the Sun, speed,
movement, temperature, and atmospheric
conditions.
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Unit 3 Lesson 4 The Terrestrial Planets
Extreme to the Core
What are the terrestrial planets?
• The terrestrial planets are the four small,
dense, rocky planets that orbit closest to the sun.
• In order by distance from the sun, these planets
are Mercury, Venus, Earth, and Mars.
• The terrestrial planets have similar compositions
and consist of an outer crust, a central core, and a
mantle that lies between the crust and core.
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Unit 3 Lesson 4 The Terrestrial Planets
What is known about Mercury?
• Mercury has a heavily cratered, moonlike surface,
composed mainly of volcanic rock. It has a
massive iron core.
• Mercury orbits the sun at a distance of 0.39
astronomical units (AU).
• One astronomical unit is the average distance
between the sun and Earth, or approximately
150 million km.
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Unit 3 Lesson 4 The Terrestrial Planets
What is known about Mercury?
• On Mercury, a day lasts almost 59 Earth days.
• The daytime temperature can rise to 427 °C, and
the nighttime temperature can drop to –174 °C.
• Mercury is the smallest planet in the solar system,
with an equatorial diameter of 4,879 km.
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Unit 3 Lesson 4 The Terrestrial Planets
What is known about Mercury?
• Mercury’s core makes up most of its volume. Its
core is thought to be partly molten.
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Unit 3 Lesson 4 The Terrestrial Planets
Harsh Planet
What is known about Venus?
• Venus’s diameter is 95 percent of Earth’s
diameter, and its mass is about 80 percent of
Earth’s.
• Because they are so similar in size, Venus is
sometimes called “Earth’s twin.” However, there
are many differences between the two planets.
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Unit 3 Lesson 4 The Terrestrial Planets
What is known about Venus?
• Earth has prograde rotation, which means that it
rotates counterclockwise about its axis as seen
from above its north pole.
• Venus has retrograde rotation, which means that
it rotates clockwise about its axis as seen from
above its north pole.
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Unit 3 Lesson 4 The Terrestrial Planets
What is known about Venus?
• It takes more time for Venus to rotate once about
its axis than it takes for the planet to revolve once
around the sun.
• The surface of Venus is covered with thousands of
volcanoes.
• Venus’s surface also has craters.
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Unit 3 Lesson 4 The Terrestrial Planets
What is known about Venus?
• The average surface temperature on Venus is
465 °C.
• Carbon dioxide in the atmosphere traps the sun’s
energy, causing surface temperatures to remain
high.
• Sulfuric acid rains down onto Venus’s surface, and
the atmospheric pressure is at least 90 times that
of Earth.
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Unit 3 Lesson 4 The Terrestrial Planets
No Place Like Home
What is special about Earth?
• Earth is the only planet that can support life.
• Earth has liquid water, an energy source, an
atmosphere that contains oxygen, and a number
of ecosystems for different organisms to inhabit.
• Matter is continuously cycled between the
environment and living things.
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Unit 3 Lesson 4 The Terrestrial Planets
What is special about Earth?
• Earth’s oceans and moderate temperatures
provided the ideal conditions for life to emerge
and flourish.
• Organisms that produced food and oxygen by
photosynthesis appeared about 3.5 billion years
ago, followed by more complex life forms.
• It is thought that between 5 million and 30 million
species of organisms currently inhabit Earth.
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Unit 3 Lesson 4 The Terrestrial Planets
What is special about Earth?
• Earth is the only terrestrial planet whose surface
is divided into tectonic plates.
• Movement of these plates causes the continents to
change positions over long periods of time.
• Tectonic plate motion, together with weathering
and erosion, has erased most surface features
older than 500 million years.
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Unit 3 Lesson 4 The Terrestrial Planets
What is special about Earth?
• The moon has a surface gravity that is only about
one-sixth that of Earth.
• The moon’s surface is heavily cratered.
• The moon’s surface has large dark areas that are
plains of solidified lava and light-colored areas
that are highlands.
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Unit 3 Lesson 4 The Terrestrial Planets
What is special about Earth?
• The moon rotates about its axis in the same time
it orbits Earth. Therefore, it keeps the same side
facing Earth.
• The lunar day is a little more than 27 Earth days.
• The moon’s surface temperature can reach 127
°C in the daytime, and it can fall to –173 °C at
night.
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Unit 3 Lesson 4 The Terrestrial Planets
Is It Alive?
What is known about Mars?
• The surface of Mars is composed largely of dark
volcanic rock.
• The surface is littered with rocks and boulders,
which are covered with a powdery dust.
• The dust is the product of chemical breakdown of
rocks rich in iron minerals. It gives the Martian
soil its orange-red color.
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Unit 3 Lesson 4 The Terrestrial Planets
What is known about Mars?
• The northern hemisphere of Mars appears to have
been covered by lava flows, and the southern
hemisphere is heavily cratered.
• Mars has large volcanoes and very deep valleys
and canyons.
• Mars has a very thin atmosphere, composed
mostly of carbon dioxide.
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Unit 3 Lesson 4 The Terrestrial Planets
What is known about Mars?
• During the Martian winter, carbon dioxide around
the planet’s poles freezes into a thin coating. This
coating vanishes during the summer.
• Winds on Mars cause giant dust storms.
• A number of features on Mars provide evidence
that liquid water once flowed on the planet’s
surface and may be found beneath the surface.
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Unit 3 Lesson 4 The Terrestrial Planets
Roving Mars
• The Mars Exploration Rovers Spirit and
Opportunity have been exploring Mars since they
landed there in January 2004.
• They are searching for evidence indicating that
water once flowed on the Martian surface and for
environments in which life may have existed.
• The surface of Mars is made up mostly of the
volcanic rock basalt, which is also found on Earth.
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